Question: Express your answer as a mixed number simplified to lowest terms. $20\dfrac{4}{12}-17\dfrac{5}{9} = {?}$
Simplify each fraction. $= {20\dfrac{1}{3}} - {17\dfrac{5}{9}}$ Find a common denominator for the fractions: $= {20\dfrac{3}{9}}-{17\dfrac{5}{9}}$ Convert ${20\dfrac{3}{9}}$ to ${19 + \dfrac{9}{9} + \dfrac{3}{9}}$ So the problem becomes: ${19\dfrac{12}{9}}-{17\dfrac{5}{9}}$ Separate the whole numbers from the fractional parts: $= {19} + {\dfrac{12}{9}} - {17} - {\dfrac{5}{9}}$ Bring the whole numbers together and the fractions together: $= {19} - {17} + {\dfrac{12}{9}} - {\dfrac{5}{9}}$ Subtract the whole numbers: $=2 + {\dfrac{12}{9}} - {\dfrac{5}{9}}$ Subtract the fractions: $= 2+\dfrac{7}{9}$ Combine the whole and fractional parts into a mixed number: $= 2\dfrac{7}{9}$